1. Field of the Disclosure
This disclosure relates generally to oilfield downhole tools and more particularly to drilling assemblies utilized for drilling deviated boreholes.
2. Background of the Art
To obtain hydrocarbons such as oil and gas, boreholes or wellbores are drilled by rotating a drill bit attached to the bottom of a drilling assembly (also referred to herein as a “Bottom Hole Assembly” or (“BHA”). The drilling assembly is attached to the bottom of a tubing, which is usually either a jointed rigid pipe or a relatively flexible spoolable tubing commonly referred to in the art as “coiled tubing.” The string comprising the tubing and the drilling assembly is usually referred to as the “drill string.” When jointed pipe is utilized as the tubing, the drill bit is rotated by rotating the jointed pipe from the surface and/or by a mud motor contained in the drilling assembly. In the case of a coiled tubing, the drill bit is rotated by the mud motor. During drilling, a drilling fluid (also referred to as the “mud”) is supplied under pressure into the tubing. The drilling fluid passes through the drilling assembly and then discharges at the drill bit bottom. The drilling fluid provides lubrication to the drill bit and carries to the surface rock pieces disintegrated by the drill bit in drilling the wellbore. The mud motor is rotated by the drilling fluid passing through the drilling assembly. A drive shaft connected to the motor and the drill bit rotates the drill bit.
A substantial proportion of current drilling activity involves drilling deviated wellbores to more fully exploit hydrocarbon reservoirs. A deviated wellbore is a wellbore that is not vertical (e.g., a horizontal borehole). In many cases, a vertical well is drilled and then a deviated branch bore is “kicked off” the vertical well. The sharper the “build radius” at the kick off point, the faster the branch bore can reach a horizontal orientation. The present disclosure provides devices, systems, and methods for achieving a high “build rate” delivering a “small build radius” as well as meeting other needs of the prior art.